As wireless communications technologies evolve, wireless communications systems become increasingly sophisticated. As such, wireless communications protocols continue to expand and change to take advantage of the technological evolution. As a result, to maximize flexibility, many wireless communications devices must be capable of supporting any number of wireless communications protocols, each of which may have certain performance requirements, such as specific out-of-band emissions requirements, linearity requirements, or the like. Further, portable wireless communications devices are typically battery powered and need to be relatively small, and have low cost. As such, to minimize size, cost, and power consumption, RF circuitry in such a device needs to be as simple, small, flexible, and efficient as is practical. Thus, there is a need for RF circuitry in an RF system that is low cost, small, simple, flexible, efficient, and conforms to wireless communications protocols.
In the RF system, traditional hybrid RF couplers may be used with RF circuits that provide matched impedances to the traditional hybrid RF couplers. Ideally, when a traditional hybrid RF coupler is coupled to an RF antenna, a nominal impedance of the RF antenna is matched to an impedance of the hybrid RF coupler. However, if the impedance of the RF antenna changes, then an impedance mismatch between the RF antenna and the hybrid RF coupler may occur, thereby degrading RF performance. A voltage standing wave ratio (VSWR) at the RF antenna is indicative of impedance changes at the RF antenna. Such changes may occur as a result of external disturbances affecting the antenna, such as a cell phone antenna contacting a user's body, a metal surface, or the like. In this regard, the VSWR at the RF antenna is an indicator of an impedance mismatch at the RF antenna. Therefore, VSWR mismatch conditions at the RF antenna may be indicative of impedance changes at the RF antenna. Such impedance changes may degrade performance of the RF system.